It seems that organisms have evolved an inherent desire or ability to reproduce and thereby pass on their genes - but how or why did reproduction first evolve? Why do genes seem to be competing for a place in the gene pool, so to speak? Has anybody read some theories?
2007-06-01 12:28:07 · 8 answers · asked by Michael H 2 in Science & Mathematics ➔ Biology
A better phrasing might be, "how did reproduction originate?"
2007-06-01 12:46:53 · update #1
There are a variety of microbe species that actually each demonstrate several different kinds of reproductive methods. They can, for example, reproduce asexually by just dividing, but they can also exchange genetic material with another microbe in something similar to sexual reproduction.
In the bacteria that can do this, it is called 'conjugation'. It doesn't usually involve an exchange of all DNA, but rather just of small, mobile rings of DNA that are called plasmids. One of the more common kinds of gene to be on a plasmid is one having to do with antibiotic resistance (more important than you might think - many bacteria naturally secrete antibiotics to get rid of other competitors for their food!).
You can see how this might be a kind of bridge to the more complicated kinds of sexual heritance we see today. Multicellular organisms have other needs and can't easily change sections of their own DNA like bacteria can, but because it is such a great advantage, they can at least create such variability in their progeny. Instead of swapping sections of DNA cell-by-cell, they might instead just develop specialized DNA exchangers... one whose pretty much sole purpose is to carry DNA segments over to another whose purpose is to recieve and integrate them.
Of course, if you're just talking about reproduction in ANY sense, there are naked chemicals that are known to do that. This is essentially what a prion (responsible for scabies and mad cow disease) is - it's a self-replicating molecule... not even life by most definitions of the term. This is less a matter of evolution than it is a matter of just how chemistry works.
2007-06-01 12:59:22 · answer #1 · answered by Doctor Why 7 · 2⤊ 0⤋
One of the main features necessary, but not sufficient, for life is replication. Reproduction (the form of replication for organisms) ocurrs many ways and some organisms even do more than one thing here on Earth.
We reproduce sexually, as do many/most animals, plants, and protists. Sexual reproduction evolved multple times. Hypotheses for the evolution of sexual reproduction include derivation of new, unique combinations of genes and traits.
Other organisms reproduce asexually, which doesn't produce novel combinations of genes except for the occasional mutation. Asexual reproduction is beneficial in situations where it is difficult to find other individuals to reproduce with or when suites of adaptive traits, or "adaptive complexes", are strongly selected for and would be essential destroyed by shuffling things the way sexual reproduction does. This has been shown in bacteria, archae, and some protists.
2007-06-01 13:47:35 · answer #2 · answered by Katia V 3 · 3⤊ 0⤋
Sexual reproduction provides the offspring with a greater diversity in their genes. This diversity increases the chance of creating variation in the genetics of the offspring. With greater diversity comes the chance of coming up with a genetic characteristic that will help the organism survive. While this also creates negative characteristics as well, the ones with the positive characteristics will be better able to gather resources and survive harsh conditions. Asexual reproduction has only mutations to rely on to create genetic diversity, while asexual reproduction has both combining of parental genes and mutations.
2007-06-02 05:09:35 · answer #3 · answered by Anonymous · 1⤊ 0⤋
It really is one of the great mysteries, one that really throws the wrench in evolution and makes you start thinking there may be something to Creationism or Grand Design Theories. So many diverse TYPES of life and different ways of reproduction.
2007-06-01 12:41:11 · answer #4 · answered by Baron_von_Party 6 · 1⤊ 3⤋
Good answer, Doctor Y - one quibble: Scabies is the result of a mite infestation; scrapie is the prion disease. You don't want to mix them up...
2007-06-01 15:34:09 · answer #5 · answered by John R 7 · 0⤊ 0⤋
Read Dr. Y and Katia. Ignore the others (even if you could make sense of all of them).
2007-06-01 14:08:27 · answer #6 · answered by georgetslc 7 · 0⤊ 0⤋
Reproduction didn't evolve... if it didn't exist from day 1, whatever organism you believe started with would have died and there would be nothing left.
2007-06-01 12:35:24 · answer #7 · answered by Violet 4 · 1⤊ 4⤋
It really is quite simple and basic. Those that did not, or lost their desire or ability to reproduce are gone.
2007-06-01 12:38:32 · answer #8 · answered by Anonymous · 2⤊ 3⤋